De-escalation of axillary surgery in clinically node-negative early-stage HR-positive, HER2-negative breast cancer.

Abstract

e12624 Background: The role of axillary surgery in early-stage breast cancer continues to evolve. While sentinel lymph node biopsy (SLNB) remains the standard for axillary staging, its therapeutic value in biologically favorable, clinically node-negative disease has been increasingly questioned. Recent randomized trials, including SOUND and INSEMA, demonstrated that omission of SLNB in selected patients does not compromise oncologic outcomes. However, prospective real-world data on structured implementation of axillary surgery omission in older patients remain limited. This study evaluated the feasibility of omitting surgical axillary staging in patients aged > 59 years with early-stage hormone receptor–positive (HR+), HER2-negative (HER2−), clinically node-negative breast cancer (BC). Methods: This prospective study included 109 patients aged > 59 years with cT1–2N0M0 HR+HER2−BC treated between 2023 and 2025 at the N.N. Petrov National Medical Research Center of Oncology. The study protocol was approved by the local ethics committee, and all patients provided written informed consent. Clinically node-negative axillary status was confirmed by axillary ultrasound, mammography, and mammoscintigraphy/breast molecular imaging using 99mTc-MIBI. Surgical axillary staging was omitted in all patients. Preoperative sentinel lymph node localization using SPECT lymphoscintigraphy was performed for adjuvant radiotherapy planning. Results: Among 109 patients initially enrolled, two were excluded from the final analysis based on postoperative pathology (one HER2 3+ tumor and one positive surgical margin), leaving 107 patients for analysis. Median age was 66 years (range 59–86), and median tumor size was 15 mm (range 4–30). Most tumors were grade 1–2 (97.2%) and cT1 (78.0%). Invasive carcinoma of no special type was the predominant histology (89.0%). Lymphovascular invasion was present in 7.4%, and an associated ductal carcinoma in situ component in 27.8%. Estrogen receptor expression was ≥90% in 96.3%, progesterone receptor expression ≥60% in 74.1%, and Ki-67 ≤20% in 87.0%. All patients received adjuvant hypofractionated or ultra-hypofractionated radiotherapy and endocrine therapy (aromatase inhibitors 83.5%, tamoxifen 16.5%); none received chemotherapy. At a median follow-up of approximately 18 months no axillary, locoregional, or distant recurrences were observed. Conclusions: These findings support the careful implementation of omission of surgical axillary staging in selected postmenopausal patients with cT1–2N0, hormone receptor–positive (HR+), HER2-negative (HER2−) breast cancer and clinically negative axillary lymph nodes. At our institution, this approach has been implemented in patients aged > 59 years with ECOG performance status < 3, tumor grade 1–2, estrogen receptor expression > 20%, and a Ki-67 proliferation index < 30%.